Head and Thieles Project

[mr_fender]

Hey all,

Just thought I'd drop a couple of pics of my latest work in progress. I building two thiele cabs and a head cab for my Mark IVa. My back is thanking me already for no longer having to lug that 90 lb little beast of a combo around anymore. With casters, it's not bad on flat ground, but stairs and lifting it up into the back of my SUV is hernia territory. The new head is about 50 lbs and each thiele is about 40 lbs, which is much easier to handle. Anyway, here's the before:

BTW, this combo cab will probably be showing up on ebay pretty soon. I'll let ya'll know before I post it.

Although not finished, here's the MKIV's new home:

This one was taken before I rounded over the corners on the head cab. The speakers include the EVM12L from my combo and a new Eminence Delta Pro 12A. The Delta sounds very similar to the EV, but has more bass and a smoother high end. They sound HUGE together.

Here's one with the rounding done and the grill frames done too:

Since these pics, I've painted the insides and faces flat black and drilled all the screw holes for the corners, handles, etc. I'll probably start on the tolex today after work. I was going to do cream tolex and oxblood stripe grills in the full fender fashion similar to the original combo cab, but decided to go the traditional black bronco and black grillcloth route. Looking at pics of cream "stacks", it didn't look right to me. I try to post some pics as I finish the tolex.

Just because I have it, here's a porn shot of naked belly of my Mark IV:

{insert cat whistle here!}

I happened to notice inside the chasis, the date 7-12-91. My baby now has a birthday! I knew it was 7-91 from the mark on the bottom, but the inside mark basically gives me a born-on-date. She's over 17 years old and still runs like a champ and sounds fantastic!

I want to take a second to thank everyone here that helped with this project, especially gts. It's been a lot of work (and fun!), and I couldn't have done it without the great info from folks here on the board. Thanks a million and wish me luck on the tolex.

 

[GIG4FUN]

wow...

I like it very much. Great work! very nice so far....

 

[trem]

Nice work Mr. Fender.

 

[kiff]

After looking at that I won't bother posting pics of the 1x12 I just made I bet you got A's in woodshop! GJ

 

[frets70]

Man that is very impressive, I'm getting ready to build a thiele for my DC-3 any tips?

 

[mr_fender]

Don't skimp on the wood. I used cabinet grade birch (11 ply I think). I got a whole sheet from Home Depot for about $50 I think. Better wood will have fewer voids, a smoother finish, and will make for better cuts and finished edges.

Check out the pics gts posted of his similar projects. The wood he used was absolutely flawless. His cabs and heads are like artwork, if you're not up to building them, he sells them.

I highly recommend a tablesaw too. I used a circular saw to rough cut and then trimmed the boards to size with a straight edge and a router. It worked fine leaving straight, square, smooth edges, but it took much longer.

I also made a circle cutting jig (a super deluxe piece of scrap plywood screwed to the bottom of my router that pivots around a drywall screw) to cut the grills and baffle holes. Just remember, it has to be a rusty drywall screw or else it won't work right! :wink:

My aim was building these on the cheap, so I had to improvise where I could. My tool shed is not as stocked as I'd like it to be. I used a doweling jig to make doweled butt joints for all the corner joints and screws for the baffle. Glue on everything too. Mesa uses dados for the baffle and lap joints for the corners. I'm new to the router, so I went the dowel route instead. Even dry fit without glue, the cabs were rock solid. I don't have any good wood clamps, so I used a couple of nylon ratchet straps to cinch the cabs together super tight while the glue dried.

I used Titebond II yellow carpenters glue. Make sure you clean up as much of the excess glue as you can before it dries. Titebond dries hard as a rock and made final sanding tougher.

As always... measure twice, cut once.

So far the tolexing is progressing nicely. I have one of the speaker cabs almost done. I just need to finish up the inside edges and assemble everthing. I'm using the non-flammable (water based?) version of Dap Weldwood contact cement, and it's working nicely. You have to let it dry for quite a while before wrapping though (30 - 40 minutes). It's slower to dry and set, but doesn't stink nearly as bad as the flammable version. It also gives you a bit more working time and is more forgiving.

I hope to finish the first thiele and tackle the head cab today, so I can assemble it and play. I've been dying to jam, and my rig is in pieces.

More updates and pics to follow.

 

[newfinator]

If you don't mind me asking, why did you add a second external layer to the baffle outside of the driver mounts on the thiele cabs?

 

[jski59]

NICE JOB! Those look great.

Although, I would think about building an open back cab while you're at it. I tried running dual Theiles with mine and much preferred the open cab/Thiele combo...even for heavier stuff.

I'm using the same speakers too. EVM in the open back, Delta Pro in the Thiele. Sounds awesome.

Jason

 

[gonzo]

man that looks fun!

thanks for sharing...

 

[mr_fender]

Hey all,

Here's an updated pic:

Not totally done yet, but getting close. I have some "Boogie" logos on the way from Mesa, and I still need to drill for the top chasis screws and mount the reverb tank. The head grill needs mounting screws too. The second cabinet still needs tolex, but the grill is done. I couldn't resist sticking the chasis in the head a making a little noise with the first finished cab. Sounds great so far. I can at least play now, and can take my time with the last cab.

The tolex is pretty tricky. My head's front corners turned out pretty good for a first timer, but not perfect. There's a tiny gap on the inside by the input jack. Luckily, I painted the wood black at all the seam locations prior to wrapping, so it's hardly noticable. The cabs are pretty simple though, since all the corners get covered. Anyway, so far so good.

 

[mr_fender]

NICE JOB! Those look great.

Although, I would think about building an open back cab while you're at it. I tried running dual Theiles with mine and much preferred the open cab/Thiele combo...even for heavier stuff.

I'm using the same speakers too. EVM in the open back, Delta Pro in the Thiele. Sounds awesome.

Jason

One step ahead of you... I actually have an extra scrap of plywood big enough to make a half back for one of the thieles just so I can try that config too. It would defeat the porting, but I'd at least be able to use both configs without building another cab.

 

[frets70]

Am I correct in saying that Mesa's Thiele dimensions are different than EV's tl806?

I am seeing +1 1/8" in width
+1 1/4" in height
and -3/4" in depth


I am no expert cab builder but does this .2 cu ft difference in size affect the speaker parameters or tone and also the cabs that come from Mesa have the c90 not the EVM.

Doesn't that defeat the purpose of the Thiele-Small Parameters? Or does the cab sound similar with C90 or EVM (my guess is that to be correctly efficient the Thiele should be designed to the TL806 plans and use an EVM 12L)

Just trying to verify before I start cutting wood

 

[kiff]

that looks totally pro! nice work man. one question though... from the first pics, before it was painted, the bottom section of the front of the head (the grill area) is solid... how do you get to the preamp tubes?

 

[frets70]

Answered my own questions (possibly) on another thread

 

[geese_com]

Nice work there. My Mark IV needs a little upgrade.

 

[ChrisCst22]

from the first pics, before it was painted, the bottom section of the front of the head (the grill area) is solid... how do you get to the preamp tubes?

Thats the way Mesa's cabinets are built too. At least my DC5 is built like that. You have to go through the back, usually removing the power tubes, to gain access to the pre's.

 

[kiff]

from the first pics, before it was painted, the bottom section of the front of the head (the grill area) is solid... how do you get to the preamp tubes?

Thats the way Mesa's cabinets are built too. At least my DC5 is built like that. You have to go through the back, usually removing the power tubes, to gain access to the pre's.

interesting, my M4 has that part held on w/ velcro and (obviously) removable. If it wasn't for that I'd probably have to take the whole thing apart to swap preamp tubes. Hell, it's hard even the way it is! lol... I have fat hands

 

[Octavarius]

from the first pics, before it was painted, the bottom section of the front of the head (the grill area) is solid... how do you get to the preamp tubes?

Thats the way Mesa's cabinets are built too. At least my DC5 is built like that. You have to go through the back, usually removing the power tubes, to gain access to the pre's.

interesting, my M4 has that part held on w/ velcro and (obviously) removable. If it wasn't for that I'd probably have to take the whole thing apart to swap preamp tubes. Hell, it's hard even the way it is! lol... I have fat hands

That's true, the never ones are made this way now. GTS also makes them that way. 8)

 

[mr_fender]

Well, I finished up the last cabinet. I'm in love with this amp even more now. It's so punchy and fat. Truely addictive. I'm waiting on my name plates from Boogie and I'll be finished. It all turned out pretty great. It was a lot of work, but well worth it. I'll post some finished pics as soon as my name plates come in.

To answer some previous questions:

The front of the head is solid in that pic because I hadn't cut out the hole for the fan yet. The preamp tubes are accessed through the back of the head. With the fan mounted to the front panel, there would be very little room to reach the preamp tubes anyway. Besides, I'm not much of a tube swapper. I just stick with Boogie tubes and never really have any problems.

The Boogie thiele's are a little different from the EV plans. The dimensions given on the price sheet and on the Boogie website are overall measurements, including the feet, corners, handle, etc. The dimensions I used for the boxes are 14 3/4" H x 18 5/8" W x 12 1/2"D. Port specs are identical to the EV plans (2.5" wide and 3.5" deep). The port extends all the way to the front of the baffle board on the Boogie thieles. The EV plans have the port offset 3/4" back to allow for the "stepdown" port cover option specified in the plans. The minute adjustments to the dimensions and internal volume of the cabinets Boogie used to make the cabs fit under the Mark heads does affect the tuning of the cabinet, but I doubt it's different enough to notice. In most aspects of design, less than a 10% difference is barely noticable. Besides, unlike PA cabinets, guitar cabinets are not designed for a flat response anyway. You want them to color the tone a bit. I used a 3/8" radius roundover bit to finish all the cab edges.

These cabs add a lot of lows. My amp sounds super FAT now! I love it. The open back combo had good dispersion, but was quite weak in the bass. As a result I always had the bass side of the graphic EQ pushed way up, and it would sometimes get a little flabby with the open back cab. Not anymore! These two little thieles have just as much big, tight bass as my old Recto 2x12 cabinets did, and they're so much lighter too. I love them.

 

[thindave]

****, those look so nice - are you open to taking orders?